Suspension and agglomeration of amidoperoxyacids

ABSTRACT

A process for the suspension agglomeration of amidoperoxyacids which leads to improved rheological storage stability of aqueous suspensions made from these agglomerated peroxyacids is disclosed. Also disclosed are aqueous suspensions of stable viscosity made by milling these agglomerates to a mean particle size of about 20 to about 75 microns.

TECHNICAL FIELD

The present invention relates to a process for agglomeration ofamidoperoxyacids which leads to improved rheological properties ofsuspensions made from these agglomerated peroxyacids. The inventionfurther relates to agglomerates made using this process, as well as aprocess for making suspensions which embodies the agglomeration processand to suspensions made from these agglomerates.

BACKGROUND OF THE INVENTION

Organic peroxyacids are useful as fabric bleaching agents. As such, theyare often formulated in the form of either dry, granular compositions,or aqueous suspensions, either of which products can be used incombination with detergent compositions.

An agglomeration process is known for diperoxydodecanedioic acid frompublished European Patent application number 0 254 331 wherein awater-impermeable material is employed as the agglomeration agent. Theseagglomerates are made in aqueous suspension at a temperature above themelting point of the water-impermeable material but below the meltingand decomposition temperatures of the peroxyacid.

However, this process suffers from the disadvantage that you must employa significant amount of a water-impermeable material as a bindermaterial in order to make such agglomerates. Use of a water-impermeablematerial in making bleaching agents is not always possible or desirable.

Amidoperoxyacids made in accordance with EP 0 349 220 have beensuccessfully suspended in aqueous suspensions but, after short storageperiods they were found to be rheologically unstable. More particularly,the amidoperoxyacid underwent a change which led to a significant,undesirable viscosity increase. Since liquid bleaching compositions mustremain pourable throughput their useful life. Products which thicken tothe point of no longer being readily pourable are not commerciallyacceptable.

Methods for suspending some peroxyacids are known from publishedEuropean Patent application number 0 347 988, published European Patentapplication number 0 435 379, published European Patent applicationnumber 0 176 124, published European Patent application 0 160 342 andpublished European patent application number 0 201 958, among others.However, none of these publications teaches or suggests a method ofpreparing a suspension of the present amidoperoxyacids which do notundergo a significant viscosity increase upon storage.

Accordingly, there exists a need in the art for rheologically stablesuspensions of amidoperoxyacids, as well as a method for making suchrheologically stable suspensions without negatively affecting one ormore of the other properties of the bleaching materials and without theneed for significant quantities of water-impermeable materials.

SUMMARY OF THE INVENTION

The present invention relates to a process for the suspensionagglomeration of amidoperoxyacids represented by the formulas I and II:##STR1## wherein R, is selected from C₁₋₁₄ alk(en)yl, ar(en)yl andalkar(en)yl, R² is selected from alkyl (ene), aryl(ene) and alkaryl(ene) groups containing from about 1-14 carbon atoms, and R³ is hydrogenor an alkyl, aryl or an aralkyl group containing from about 1 to about10 carbon atoms; comprising the steps of:

A. preparing an aqueous suspension having a pH of from 2-6 of acomposition comprising at least one of said amidoperoxyacids,

B. agglomerating said aqueous suspension of peroxyacid at a temperature0-20° C. below the melting point of said peroxyacid composition, and

C. cooling said agglomerated peroxyacid composition to a temperaturebelow 30° C.

The present invention also relates to amidoperoxyacid agglomerates madeby this process, a process for making suspensions which employs theaforementioned agglomeration process and to suspensions made fromagglomerates which are produced in accordance with the above-describedprocess.

It has surprisingly been found that the agglomeration ofamidoperoxyacids at elevated temperature leads to an agglomerate whichlends itself to the making of theologically stable suspensions inaqueous suspension systems. More particularly, suspensions made withagglomerates that are produced at elevated temperature remain pourablethroughout an acceptable storage period, when compared with the priorart suspensions of the same types of peroxyacid materials.

The invention and its further advantages will be explained in greaterdetail in the description which follows.

DETAILED DESCRIPTION OF THE INVENTION

Peroxyacids are synthesized, suspended in an aqueous suspension at a pHof from 2-6 and agglomerated. The agglomerated peroxyacid can then beused as a bleaching agent either alone or in combination with adetergent composition.

The present invention applies to amidoperoxyacids.

The amidoperoxyacids can be represented by the formulas I and II:##STR2## wherein R¹ is selected from C₁₋₁₄ alk(en)yl, ar(en)yl, andalkar(en)yl, R² is selected from alkyl (ene), aryl (ene) andalkaryl(ene) groups containing from about 1-14 carbon atoms, and R³ ishydrogen or an alkyl, aryl or an aralkyl group containing from about 1to about 10 carbon atoms. These amidoperoxyacids and methods for makingthem are described in U.S. Pat. Nos. 4,634,551 and 4,686,063, both ofwhich are hereby incorporated by reference.

Preferred amidoperoxyacids are those having the following formula III:##STR3## wherein R¹ is an alkyl group containing from 6-12 carbon atomsand R2 is an alkylene group containing 1-6 carbon atoms. The mostpreferred amidoperoxacids are 4-nonylamido-4-oxoperoxybutanoic acid and6-nonyl amido-6-oxoperoxyhexanoic acid.

At the end of the typical peroxyacid synthesis the reaction is quenchedwith water, the products are filtered, washed with water to removeexcess acid and filtered again. The peroxyacid wet cake thus obtainedmay be further processed in accordance with the process of the presentinvention in order to form either agglomerates of the peroxyacid orsuspensions thereof.

The first step in the process of the present invention is to prepare theaqueous suspension media. Aqueous suspension media is set at a pH ofbetween 2 and 6 by addition of an appropriate amount of pH adjustingagent such as an acid or base. The exact pH to be employed will dependto some extent on the particular peroxyacid to be agglomerated. Forexample, with the preferred amidoperoxyacids a preferred pH is 4.0-5.5with pH 4.5 being the most preferred when agglomerating anamidoperoxyacid of the formula III.

The aqueous suspension media, in which the agglomeration is carried out,may also contain one or more optional ingredients including bufferingagents, exotherm control agents and chelating agents, for example.

In another preferred embodiment of the invention the aqueous suspensionmedia contains a phosphate buffer which is preferably orthophosphate orpyrophosphate in a concentration range of from 0.01 molar to 1.0 molar.Most preferred is a 0.10 molar solution of orthophosphates. These can beselected from the group of phosphoric acid, monobasic sodium phosphate,dibasic sodium phosphate and tribasic sodium phosphate. The finalsolution must have a pH between 2 and 6, and more preferably between 4and 5.5. The pH of the buffered solution can be adjusted to theappropriate range by addition of sodium hydroxide, for example. Ofcourse, other cations such as potassium may be employed in the bufferingagent.

Chelants may also optionally be incorporated in the aqueous suspensionmedia. Examples of suitable chelants for use herein are carboxylates,such as ethylene diamine tetraacetate (EDTA) and diethylene triaminepentaacetate (DTPA); polyphosphates, such as sodium acid pyrophosphate(SAPP), tetrasodium pyrophosphate (TSPP) and sodium tripolyphosphate(STPP); phosphonates, such as ethylhydroxydiphosphonate (Dequest® 2010)and other sequestering agents sold under the Dequest® tradename;dipicolinic acid, picolinic acid, citric acid and 8-hydroxyquinoline;and combinations of the above.

Preferably 0.01-10% of such chelants are employed. More preferably,0.1-5.0% of chelant is employed. All amounts in this patent applicationare percentage by weight; based on the total weight of the particularcomposition in question, unless otherwise specified.

The peroxyacid composition is preferably suspended prior toagglomeration in the form of a wet cake which is fresh from thesynthesis process. A typical composition will contain 30-60% by weightof peroxyacid, 35-65% by weight water and the balance organic impuritieswhich comprise mainly unreacted starting materials from the synthesisprocess.

The peroxyacid wet cake is mixed into the aqueous suspension media by asuitable mixing or agitating apparatus. For example, a double-armedturbine stirrer can be used for this mixing.

The peroxyacid may be added to the aqueous suspension media at anytemperature below the decomposition temperature of the peroxyacid suchas room temperature, but, in a preferred embodiment, the aqueoussuspension media is first warmed to a temperature which is 0-20° C.below the melting point of the peroxyacid composition. Then, theperoxyacid is added thereto. In this manner, decomposition of theperoxyacid, which may occur at elevated temperatures, is kept to aminimum. Most preferably, the aqueous suspension media is 5-15° C. belowthe melting point of the peroxyacid composition when the peroxyacid isadded.

Since the suspension media is aqueous, this places a limitation of 100°C. on the agglomeration temperature. However, peroxyacid compositionshaving a higher melting point can still be agglomerated by the presentprocess. More particularly, a material can be added to the aqueoussuspension media which does not adversely affect the peroxyacid or theagglomeration process and effectively elevates the boiling point of thesuspension media. Certain salts and glycols could be employed.

Another alternative is to employ one or more fatty alcohols, fatty acidsor fatty esters as diluents in the peroxyacid composition whereby themelting point of the peroxyacid composition can be depressed below 100°C. A particularly suitable material is lauric acid.

After addition of the peroxyacid composition to the aqueous suspensionmedia, if necessary, the pH is returned to 2-6 by further addition ofthe appropriate agent, in this case normally sodium hydroxide.

Once the peroxyacid composition has been added to the aqueous suspensionmedia, the suspension is warmed to an agglomeration temperature of 0-20°C. below the melting point of the peroxyacid composition to therebyagglomerate said peroxyacid composition into agglomerates of the desiredsize. The agglomeration is continued until the agglomerates are the sizewhich is desired.

Agglomeration occurs as a result of the partial melting of theperoxyacid composition which then agglomerates with itself.Agglomeration normally occurs in a short time period of about 20-60minutes, depending upon how close the agglomeration temperature is tothe melting point of the peroxyacid composition. The desired size of theagglomerates is generally from 200 to 2000 μm, although other sizes arealso possible.

Once the agglomerates are of the desired size, the agglomerated materialis cooled to below 30° C. This cooling step is preferably a rapidcooling to minimize peroxyacid decomposition and to prevent furtherbuildup of the agglomerates beyond the desired size. The agglomeratesmay then by separated by filtration.

The agglomerates generally comprise the peroxyacid, some stabilizer,some organic impurities and the balance water. A typical agglomeratewill contain 30-70% by weight of peroxyacid, and perhaps more if theagglomerate is subjected to drying.

The agglomerates produced by the present process are physicallydifferent than agglomerates produced at an agglomeration temperature of20-30° C., for example. It is this physical difference which makes itpossible to stably suspend these agglomerates in a liquid bleachingagent suspension which remains theologically stable over long storageperiods. For example, when compared to suspensions made directly fromperoxyacid wet cake, the present suspensions do not exhibit theundesirable viscosity increase which is observed in the case where theperoxyacid was suspended without a prior agglomeration step.Accordingly, the agglomerates are an improvement over existingagglomerates of these peroxyacids.

In another embodiment of the present invention, the peroxyacidagglomerates are further processed into stable, bleaching suspensions,either in the same vessel in which they were agglomerated, or in atwo-step process.

In particular, the suspension may be made by adding sufficient water tothe agglomerates to act as the suspension media and then adding from 0.1to 1.0 weight percent, based on said suspension, xanthan gum and 0.02 to2.0 weight percent, based on said suspension, of a second polymerselected from polyvinyl alcohol, one or more cellulose derivatives, andmixtures thereof. The suspension is most preferably made under highshear conditions, such as with an Ultra-Turrax® stirring apparatus.

Aqueous surfactant structured liquids are also capable of suspending thepresent peroxyacid agglomerates without the need of a thickening agentand can be obtained by using a single surfactant or mixtures ofsurfactants in combination with an electrolyte.

The preparation of surfactant-based suspending liquids normally requiresa nonionic and/or an anionic surfactant and an electrolyte, though othertypes of surfactant or surfactant mixtures, such as the cationics andzwitterionics, can also be used. Indeed, various surfactants orsurfactant pairs or mixtures can be used in combination with severaldifferent electrolytes, but it should be appreciated that electrolyteswhich would readily be oxidised by peroxy acids, such as chlorides,bromides and iodides, and those which are not compatible with thedesired acid pH range, e.g. carbonates and bicarbonates, shouldpreferably be excluded from the peroxy acid suspending surfactant liquidcompositions of the invention.

Examples of different surfactant/electrolyte combinations suitable forpreparing the peroxy acid suspending surfactant structured liquids are:

a) surfacants:

(i) coconut diethanolamide/alkylbenzene sulphonate;

(ii) C₉ -C₁₆ alcohol ethoxylate/alkylbenzene sulphonate;

(iii) lauryl ethersulphate/alkylbenzene sulphonate;

(iv) alcohol ether sulphate;

in combination with:

b) electrolytes:

(i) sodium sulphate and/or

(ii) sodium nitrate.

Accordingly, another suspension in accordance with the inventionencompasses aqueous liquid bleaching compositions comprising aneffective amount of a solid, particulate, substantially water-insolubleamido peroxyacid stably suspended in an aqueous liquid containing asurfactant and an electrolyte, said compositions having an acid pH inthe range of from 2 to 6, preferably from 4 to 5.5.

This suspension of the invention may contain from about 1 to 40% byweight of the peroxy acid, preferably from 2.5 to about 30% by weight.

As explained, the surfactants usable in this embodiment can be anionic,nonionic, cationic, zwitterionic or soap in nature or mixtures thereof.

The anionics comprise the well-known anionic surfactants of the alkylaryl sulphonate type, the alkyl sulphate and alkyl ether sulphate types,the alkane and alkene sulphonate type etc. In these surfactants thealkyl radicals may contain from 9-20 carbon atoms. Numerous examples ofsuch materials can be found in Schwartz, Perry, Vol. II, 1958,"Detergents and Surface Active Agents".

Specific examples of suitable anionic surfactants include sodium laurylsulphate, potassium dodecyl sulphonate, sodium dodecyl benzenesulphonate, sodium salt of lauryl polyoxyethylene sulphate, dioctylester of sodium sulphosuccinic acid and sodium lauryl sulphonate.

The nonionics comprise ethylene oxide and/or propylene oxidecondensation products with alcohols, alkylphenol, fatty acids and fattyacid amides. These products generally contain 5 to 30 ethylene oxideand/or propylene oxide groups. Fatty acid mono- and dialkylolamides, aswell as tertiary amine oxides are also included in the terminology ofnonionic detergent-active materials.

Specific examples of nonionic detergents include nonyl phenolpolyoxyethylene ether, tridecyl alcohol polyoxyethylene ether, dodecylmercaptan polyoxyethylene thioether, the lauric ester of polyethyleneglycol, C₁₂ -C₁₅ primary alcohol/7 ethylene oxide, the lauric ester ofsorbitan polyoxyethylene ether, tertiary alkyl amine oxide and mixturesthereof.

Other examples of nonionic surfactants can be found in Schwartz, Perry,Vol. II, 1958, "Detergents and Surface Active Agents" and Schick, Vol.I, 1967, "Nonionic Surfactants".

The cationic detergents which can be used in the present inventioninclude quaternary ammonium salts which contain at least one alkyl grouphaving from 12 to 20 carbon atoms. Although the halide ions are thepreferred anions, other suitable anions include acetate, phosphate,sulphate, nitrite, and the like.

Specific cationic detergents include distearyl dimethyl ammoniumchloride, stearyl dimethyl benzyl ammonium chloride, stearyl trimethylammonium chloride, coco dimethyl benzyl ammonium chloride, dicocodimethyl ammonium chloride, cetyl pyridinium chloride, cetyl trimethylammonium bromide, stearyl amine salts that are soluble in water such asstearyl amine acetate and stearyl amine hydrochloride, stearyl dimethylamine hydrochloride, distearyl amine hydrochloride, alkylphenoxyethoxyethyl dimethyl ammonium chloride, decyl pyridinium bromide,pyridinium chloride derivative of the acetyl amino ethyl esters oflauric acid, lauryl trimethyl ammonium chloride, decyl amine acetate,lauryl dimethyl ethyl ammonium chloride, the lactic acid and citric acidand other acid salts of stearyl-1-amido-imidazoline with methylchloride, benzyl chloride, chloroacetic acid and similar compounds,mixtures of the foregoing, and the like.

Zwitterionic detergents include alkyl-β-iminodipropionate,alkyl-β-aminopropionate, fatty imidazolines, betaines, and mixturesthereof.

Specific examples of such detergents are1-coco-5-hydroxyethyl-5-carboxymethyl imidazoline, dodecyl-β-alanine,the inner salt of 2-trimethyl amino lauric acid, andN-dodecyl-N,N-dimethyl amino acetic acid.

The total surfactant amount in the liquid bleaching suspension of theinvention may vary from 2 to 50% by weight, preferably from 5 to 35% byweight, depending on the purpose of use. In the case of suspendingliquids comprising an anionic and anonionic surfactant the ratio thereofmay vary from about 10:1 to 1:10. The term anionic surfactant used inthis context includes the alkali metal soaps of synthetic or naturallong-chain fatty acids having normally from 12 to 20 carbon atoms in thechain.

The total level of electrolyte(s) present in the composition to providestructuring may vary from about 1.5 to about 30%, preferably from 2.5 to254 by weight.

When suspending the agglomerates of the present invention it isimportant to mill the agglomerated peroxyacid composition so that themajority of the particles are less than 150 μm in diameter. A preferredparticle size range is from 1-150 μm with a mean particle size in thearea of 20-75 μm.

The resultant suspensions are also physically different from prior artsuspensions of the same peroxyacids, as shown by their extendedrheological stability which is demonstrated in the examples appendedhereto. These suspensions can be used as liquid bleaching compositionseither alone, in combination with powdered detergents as a two componentsystem, or in combination with liquid detergents either as atwo-component system or as a one-component system wherein the detergentand bleaching composition are combined into one liquid.

The bleaching compositions of the present invention have been found tohave the same level of activity as the prior art suspensions, the samelevel of chemical stability and a much higher level of rheologicalstability.

The present invention will be further exemplified by the examples whichfollow. These examples are not to be interpreted as limiting theinvention in any way and the scope of the invention is to be determinedfrom the claims appended hereto.

EXAMPLE 1

A 2 liter aqueous buffer solution containing 5% by weight of monobasicsodium phosphate and 1% by weight of Dequest® 2010 was adjusted to a pHof 4.5 with a solution of sodium hydroxide. The buffer solution waswarmed to 60° C. with stirring at about 400 rotations per minute. Oncethe buffer solution reached 60° C., 600 grams of6-nonylamido-6-oxoperoxyhexanoic acid wet cake containing 35% by weightof 6-nonylamido-6-oxoperoxyhexanoic acid, 4% by weight of organicimpurities and the balance water, was added with continued stirring. ThepH was again adjusted to 4.5. Heating was continued until theagglomerates were of the desired size (at about 69° C.) at which pointthe agglomerates were rapidly cooled to less than 30° C. Theagglomerates were then separated from the water with a glass filter. Ayield of 300 grams of agglomerates containing about 62% by weight of6-nonylamido-6-oxoperoxyhexanoic acid was obtained.

The agglomerates were then used to prepare a bleach suspension with thefollowing composition:

10.2% 6-nonylamido-6-oxoperoxyhexanoic acid (calculated on pure, dryperoxyacid),

0.25% dipicolinic acid,

1.0% polyvinyl alcohol,

0. 5% xanthan gum, and the balance water.

The suspension was prepared by first mixing the polyvinyl alcohol,xanthan gum, dipicolinic acid and water with a turbine stirrer for onehour. Next, the peroxyacid agglomerates were admixed and the pH wasadjusted to 4.5 with a sodium hydroxide solution. The suspension wasfinely milled with an Ultra Turrax® T₅₀ rotor-stator dissolver to a meanparticle size of 33 μm and a maximum particle size of approximately 150μm.

The viscosity of the suspension was 34 mPa's at a shear rate of 200 s⁻¹.After 4 weeks storage at 40° C. the viscosity was 77 mPa's. Thesuspension remained pourable for the entire storage period.

Comparative Example A

Starting with the same peroxyacid wet cake as was used for theagglomeration step of Example 1, a suspension was prepared in accordancewith Example 1 except that the peroxyacid wet cake was not agglomerated.A suspension with a mean particle size of 13 μm and an approximatemaximum particle size of 100 μm was obtained. This suspension waspourable having an initial viscosity of 32 mPa's. After 1week storage at40° C. a gel structure had formed and the suspension was no longerpourable. After stirring a viscosity of 350 mPa's was measured, but uponfurther storage at 40° C the gel structure reformed.

EXAMPLE 2

In the same manner as Example 1, peroxyacid wet cake was agglomerated.The agglomerates were then used to prepare a suspension using 1 aurylalkyl sulphonate and sodium toluene sulphonate as the suspending agents.A thin, pourable suspension was obtained with a mean particle size of 23μm and an approximate maximum particle size of 130 μm. The viscosity wasfound to be 10 mPa's. After 1 week storage at 40° C. the viscosity was78 mPa's and the suspension remained pourable. After two weeks storageat 40° C. the viscosity was 72 mPa's and the suspension remainedpourable.

Comparative Example B

The procedure of Example 2 was repeated except that peroxyacid wet cakewas used to prepare the suspension, without first agglomerating it. Thesuspension was thin and pourable having a mean particle size of 13 μmand an approximate maximum particle size of 67 pro. The viscosity of thesuspension was 19 mPa's. After 1 week storage at 40° C. a gel had formedand the suspension was no longer pourable. After stirring the viscositywas measured at 250 mPa's. After an additional week of storage at 40° C.the gel structure had returned and the viscosity after stirring wasmeasured at 380 mPa's.

EXAMPLE 3

To 600 ml demineralized water 3.2 g dipicolinic acid was added and thepH was adjusted to 3.0 with a solution of sodium hydroxide. 595 grams of4-nonylamido-4-oxoperoxybutanoic acid wet cake containing 34.4% byweight of peroxyacid, 3.5% by weight of organic impurities, and thebalance water, was added with stirring at about 400 rotations perminute. The pH was again adjusted to 3.0.

The mixture was heated under continuous stirring until agglomerates wereobtained of the desired size (at about 63° C.). Next the mixture wascooled to below 30° C. and a bleach suspension was prepared by adding12.6 grams polyvinyl alcohol and 2.5 grams xanthan gum, mixing for onehour and finally milling the suspension with and Ultra Turrax® T50rotor-stator dissolver to a mean particle size of 28 μm and a maximumparticle size of approximately 150 μm.

The composition of this suspension was:

16.2% 4-nonylamido-4-oxoperoxybutanoic acid (calculated on pure, dryperoxyacid),

0.25% dipicolinic acid,

1.0% polyvinyl alcohol,

0.2% xanthum gum, and the balance water.

The viscosity of the suspension was 48 mPa.s at a shear rate of 200 s⁻¹.After two weeks storage at 40° C. the viscosity was 130 mPa.s and after4 weeks it was 165 mPa.s. It remained pourable.

Comparative Example C

Starting with the same 4-nonylamido-4-oxoperoxybutanoic acid wet cake aswas used for the agglomeration step of example 3 a suspension wasprepared with the same composition as in example 3, except that theperoxyacid was not agglomerated. A suspension with a mean particle sizeof 9 μm and a maximum particle size of 43 μm was obtained. Thissuspension had an initial viscosity of 45 mPa.s but after I week storageat 40° C. a gel structure had formed and the suspension was no longerpourable. After stirring a viscosity of 770 mPa.s was found. Uponfurther storage at 40° C. the gel structure returned.

EXAMPLE 4

A suspension was prepared starting with peroxyacid agglomerates asdescribed in Example 1 using the following composition:

10.04 6-nonylamido-6-oxoperoxyhexanoic acid (calculated on pure, dryperoxyacid),

6.34 Sodium alkyl benzene sulphonate,

2.74 C₁₂ -C₁₅ primary alcohol/ethylene oxide,

6.34 anhydrous sodium sulphate, and balance water + NaOH for pH adjustedto 4.5.

The suspension was finely milled with an Ultra Turrax rotor-statordissolver to a mean particle size of 29 μm and a maximum particle sizeof approximately 76 μm.

The viscosity of the suspension was 265 mPa.s at a shear rate of 200s⁻¹, after one week storage at 40° C. the viscosity was 365 mPa.s andafter two weeks at 40° C. the viscosity was 540 mPa.s. It remainedpourable for the entire storage period.

Comparative Example D

A suspension was prepared with the same composition as in Example 4 butstarting with the peroxyacid wet cake without prior agglomeration. Asuspension with a mean particle size of 19 μm and a maximum particlesize of 105 pm was obtained.

The initial viscosity of this suspension was 385 mPa.s. After 1 weekstorage a gel structure had formed and it was no longer pourable.

The gel structure was broken by stirring and a viscosity of 600 mPa.swas measured.

After 2 weeks storage the gel structure had returned. It was broken bystirring and a viscosity of 660 mPa.s was found.

What is claimed is:
 1. A process for preparing rheologically stablesuspensions of suspension agglomerated amidoperoxyacid which remainpourable throughout acceptable storage periods wherein saidamidoperoxyacids are represented by the formulas I and II: ##STR4##wherein R¹ is selected from C₁₋₁₆ alk(en)yl, ar(en)yl and alkar(en)yl,R² is selected from alky(ene), aryl(ene) and alkaryl(ene) groupscontaining from about 1-14 carbon atoms, and R³ is hydrogen or an alkyl,aryl or an aralkyl group containing from about 1 to about 10 carbonatoms; and wherein said process comprises:A. preparing an aqueoussuspension having a pH of from 2-6 of a composition comprising at leastone of said amidoperoxyacids, B. agitating said aqueous suspension ofperoxyacid of step A at a temperature 0-20° C. below the melting pointof said peroxyacid composition for a time sufficient to formagglomerates having a particle size of 200-2000 μm; C. milling theagglomerates to a mean particle size of form about 20 to about 75 μm; D.cooling said agglomerated peroxyacid composition to a temperature below30° C.; and E. suspending the agglomerated peroxyacid in an aqueousmedia in order to form a suspension having from about 1-40% by weightperoxyacid.
 2. The process of claim 1 wherein step A comprises preparingan aqueous suspension media having a pH of from 2-6, heating saidaqueous suspension media to a temperature 0-20° C. below the meltingtemperature of the peroxyacid and adding said peroxyacid to said heatedaqueous suspension media.
 3. The process of claim 1 wherein saidperoxyacid is selected from 4-nonylamido-4-oxoperoxybutanoic acid and6-nonylamido-6oxoperoxyhexanoic acid.
 4. The process of claim 1 whereinstep A further comprises contacting said peroxyacid with a buffersolution.
 5. The process of claim 1 wherein said aqueous suspensionmedia in which said peroxyacid composition is agglomerated, comprises0.01-10 weight percent of a chelating agent.
 6. The process of claim 1wherein step D comprises suspending the agglomerated peroxyacid in anaqueous medium comprising 0.1 to 1.0 weight percent, based on saidsuspension, of xanthan gum and 0.02 to 2.0 weight percent, based on saidsuspension, of a second polymer selected from polyvinyl alcohol, one ormore cellulose derivatives, and mixtures thereof.
 7. The process ofclaim 1 wherein step D comprises suspending the agglomerated peroxyacidin an aqueous medium containing 2-50 weight percent of a surfactant and1.5 to 30 weight percent of an electrolyte.
 8. A liquid peroxyacidbleaching composition which comprises the suspension of claim
 1. 9. Adetergent composition comprising the liquid peroxyacid bleachingcomposition of claim 8.